849
FXUS10 KWNH 241641
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1239 PM EDT WED JUN 24 2020
VALID JUN 24/1200 UTC THRU JUN 28/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER ONTARIO/QUEBEC
TROUGH CROSSING THE EASTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE UPPER-LEVEL LOW IN PLACE OVER THE NORTHERN GREAT LAKES IS
EXPECTED TO LIFT NORTH/NORTHEASTWARD OVER THE NEXT FEW DAYS WHILE
THERE WILL BE SOME SOUTHWARD EXPANSION ON THE LONGWAVE TROUGH OVER
THE EASTERN U.S., WHICH PUSHES A COLD FRONT THROUGH MUCH OF THE
MID-ATLANTIC AND NEW ENGLAND BEFORE WASHING OUT OVER THE
SOUTHEAST. FROM A SYNOPTIC POINT OF VIEW, MASS FIELDS ARE IN GOOD
SHAPE IN THE REGION AND A GENERAL MODEL BLEND IS PREFERRED.
SHORTWAVE CROSSING THE PACIFIC NORTHWEST AND PLAINS/MIDWEST
ENERGY DIGGING INTO THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND...NORTHERN STREAM
12Z NAM/GFS AND 00Z UKMET BLEND...SOUTHERN STREAM
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE LATEST GUIDANCE CONTINUES TO ADVERTISE A SHORTWAVE TROUGH
CROSSING THE PACIFIC NORTHWEST THROUGH TONIGHT AND THEN ADVANCING
PROGRESSIVELY DOWNSTREAM ACROSS THE CENTRAL/NORTHERN ROCKIES GOING
THROUGH THURSDAY. AS THIS IS OCCURRING, SOME OF THE ENERGY WILL BE
SEPARATING OUT AND DIGGING FARTHER SOUTH INTO THE SOUTHWEST. GOING
THROUGH FRIDAY AND SATURDAY, THE NORTHERN PORTION OF THE ORIGINAL
TROUGH WILL EJECT OUT ACROSS THE NORTHERN PLAINS AND UPPER
MIDWEST, WITH THE GUIDANCE FAVORING A SOUTHERN STREAM TROUGH
LINGERING NEAR THE FOUR CORNERS REGION. WITH THE INITIAL SURGE OF
THE NORTHERN STREAM PORTION OF THE TROUGH, THE MODELS ARE IN GOOD
AGREEMENT ALTHOUGH THE 00Z UKMET SHOWS A MORE PROGRESSIVE TROUGH
COMPARED TO THE OTHER MODELS BY THE END OF THE PERIOD AS THE
ENERGY CROSSES THE GREAT LAKES REGION. WILL PREFER A NON-UKMET
BLEND AS A RESULT WITH THIS NORTHERN STREAM TROUGH EVOLUTION.
WITH THE SOUTHERN STREAM ENERGY, THE 00Z ECMWF TENDS TO HOLD
ENERGY BACK A BIT MORE TO THE WEST AND OVER THE DESERT SOUTHWEST
VERSUS THE MODEL CONSENSUS WHICH IS A LITTLE CLOSER TO THE BROADER
FOUR CORNERS REGION. THE 00Z CMC THOUGH APPEARS TO BE MUCH TOO
PROGRESSIVE AND GENERALLY TOO WEAK AS IT DRIVES ENERGY MUCH
FARTHER EAST BY THE END OF THE PERIOD. THE BETTER MODEL CLUSTERING
AND ENSEMBLE SUPPORT FAVORS A BLEND OF THE 12Z NAM/GFS AND 00Z
UKMET FOR THE TIME BEING, AND SO A BLEND OF THESE SOLUTIONS WILL
BE PREFERRED FOR THE SOUTHERN STREAM ENERGY.
STRONG SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST THIS WEEKEND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 06Z GEFS/00Z ECENS MEAN
CONFIDENCE: AVERAGE
A STRONG SHORTWAVE TROUGH FROM THE GULF OF ALASKA IS FORECAST TO
DROP SOUTH ALONG THE BRITISH COLUMBIA COAST AND ARRIVE ACROSS THE
PACIFIC NORTHWEST BY SATURDAY MORNING. WITH THE INITIAL SURGE OF
HEIGHT FALLS, THE 12Z NAM AND 00Z ECMWF ARE A BIT SLOWER COMPARED
TO THE 12Z GFS, 00Z ECMWF AND 00Z CMC SOLUTIONS. HOWEVER, THERE IS
MORE SPREAD WITH A JET-STREAK AND SECONDARY SHORTWAVE DIVING SOUTH
LATE SATURDAY ALONG THE BRITISH COLUMBIA COAST. THE NAM AND UKMET
SOLUTIONS ARE MORE PRONOUNCED WITH THIS FEATURE VERSUS THE MORE
SUBTLE GFS AND ECMWF. THE CMC ACTUALLY IS THE WEAKEST WITH THIS
SECONDARY PIECE OF ENERGY. THE 06Z GEFS MEAN AND 00Z ECENS MEAN
SUPPORT A COMPROMISE SOLUTION BETWEEN THE CAMPS, AND A BLEND OF
THESE SOLUTIONS WILL BE PREFERRED TO ATTEMPT TO RESOLVE SOME OF
THE TIMING/DEPTH DIFFERENCES.
LOWER MS VALLEY AND GULF COAST STATES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS/HREF
CONFIDENCE: AVERAGE
WEAK FLOW ALOFT WITH PIECES OF SHORTWAVE ENERGY BECOMING REMOVED
FROM THE WESTERLIES WILL DRIFT OVER THE TEXAS GULF COAST AND LOWER
MS VALLEY OVER THE NEXT COUPLE OF DAYS. THE MODELS ARE IN SOMEWHAT
BETTER AGREEMENT TODAY WITH GRADUALLY TAKING THIS ENERGY OFF TO
THE EAST-NORTHEAST AND SHEARING IT OUT ACROSS THE GULF COAST
STATES. HOWEVER, THE 00Z NON-NCEP MODELS ARE ALL A BIT MORE
PROGRESSIVE IN DOING THIS AS ALL OF THE 12Z HREF GUIDANCE AND THE
12Z NAM/GFS SOLUTIONS ARE SLOWER AND TEND TO KEEP THE ENERGY
LINGERING OVER THE WESTERN GULF COAST AND LOWER MS VALLEY REGION
FOR LONGER. WILL PREFER A BLEND OF THE NON-NCEP GUIDANCE AS A
RESULT FOR NOW.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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